Almost 47 million people around the world have some form of dementia, a number that is projected to double every 20 years, according to the “World Alzheimer Report 2015, The Global Impact of Dementia: An Analysis of Prevalence, Incidence, Cost, and Trends” (http://bit.ly/1LxgPfL).

This is the seventh annual report compiled by Alzheimer’s Disease International, a United Kingdom–based federation of national Alzheimer associations. Based on new data, the report increased estimates of new cases of dementia over previous estimates by 12% to 13%. The authors note that these changes do not reflect trends toward increasing dementia, only better sampling. Low- and middle-income countries will be disproportionately affected due to more rapid population aging.